How are Lyα Absorbers in the Cosmic Web Related to Gas-rich Galaxies?

We present the correlation between Ly α absorbers and H i galaxies in the nearby universe (0.01 ≤ z ≤ 0.057). We find that Ly α absorbers are strongly correlated to H i galaxies at a projected separation of ≤0.5 Mpc and velocity separation of ≤50 km s −1 . Ly α absorbers are 7.6 times more likely to...

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Bibliographic Details
Published in:The Astrophysical journal 2022-01, Vol.924 (2), p.123
Main Author: Borthakur, Sanchayeeta
Format: Article
Language:English
Subjects:
Absorbers
Astrophysics
Circumgalactic medium
Correlation
Disks
Emission line galaxies
Galaxies
Galaxy distribution
H I line emission
Intergalactic medium
Lyman alpha forest
Lyman-alpha forest clouds
Separation
Stars & galaxies
Velocity
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Summary:We present the correlation between Ly α absorbers and H i galaxies in the nearby universe (0.01 ≤ z ≤ 0.057). We find that Ly α absorbers are strongly correlated to H i galaxies at a projected separation of ≤0.5 Mpc and velocity separation of ≤50 km s −1 . Ly α absorbers are 7.6 times more likely to be found near H i galaxies compared to a random distribution. The strength of correlations drops as the projected and/or velocity separation increases. We also find the correlation between Ly α absorbers and H i galaxies to be stronger than those observed between Ly α absorbers and optically selected galaxies. There is an enhancement in the number of absorbers at velocity separations of ≤30 km s −1 from galaxies at distances larger than their viral radius. Combined with the fact that most of our galaxies are not driving strong outflows, we conclude that the absorbers at low-velocity separations are tracing reservoirs of cooler gas around galaxies. This conclusion is consistent with the predictions from cosmological simulations where faint gas from the IGM flows into the disks of galaxies leading to galaxy growth.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ac3133